Dielectric barrier discharge lamps become hot during operation, so that the dielectric barrier discharge lamp may break due to different thermal expansion of its parts. Thus, it is necessary in many cases to cool the dielectric barrier discharge lamp by means of a coolant like water.
From U.S. Pat. No. 5,666,026 a dielectric barrier discharge lamp is known, which comprises an inner tube arranged inside an outer tube, wherein between the inner tube and the outer tube a discharge gas for providing ultraviolet light is sealed. An outer electrode is provided on the outside of the outer tube and an inner electrode is provided on the inside of the inner electrode, so that the tubes provide a dielectric barrier and a discharge arc between the electrodes may occur for stimulating the discharge gas to emit ultraviolet light. The inner electrode is provided as mainly tubular bush comprising a slit, so that the tubular inner electrode contacts the inner tube in a spring-loaded manner for electrical contact. Due to the spring-loaded inner electrode different thermal expansions of the inner tube and the inner electrode are compensated, so that an external cooling may be rendered unnecessary.
It is a disadvantage of such kind of a dielectric barrier discharge lamp that the inner tube is applied by a comparable high mechanical stress due to the spring-loaded inner electrode leading to a low life time. Further the positioning of the inner electrode inside the inner tube is difficult and have to be performed by means of a special tool. This leads to a big size of the inner tube as well as the lamp and renders the production expensive.